Apparatus for solvent extraction of catalyst from polymer solids



Oct. 17, 1967 T. PRICE ETAL 3,347,637

APPARATUS FOR SOLVENT EXTRACTION OF CATALYST FROM POLYMER SOLIDS 3Sheets-Sheet 1 Original Filed June 5, 1961 SOLVENT AN D SOLUBLEMATERIALS FRESH SOLVENT 4 E m m N 8 EE MB m 0 S MATERIALS POLYMER SOLIDSFIG.

INVENTORS J.S.SCOGGIN BY L.T. PRICE A r TOAWEYS Oct. 17, 1967 L. T.PRICE ETAL APPARATUS FOR SOLVENT EXTRACTION OF CATALYST FROM POLYMERSOLIDS Original Filed June 5, 1961 ATTORNEYS Oct. 17, 1967 T. PRICE ETAL3,347,637

APPARATUS FOR SOLVENT EXTRACTION OF CATALYST FROM POLYMER SOLIDSOriginal Filed June 5, 1961 3 Sheets-Sheet, 3

STORAGE ATTORNEYS United States Patent 3,347,637 APPARATUS FOR SOLVENTEXTRACTION 0F (IATALYST FROM POLYMER SOLIDS Lowell T. Price and Jack S.Scoggin, Bartlesville, Okla,

assignors to Phiilips Petroleum Company, a corporation of DelawareOriginal application June 5, 1961, Ser. No. 114,727, now Patent No.3,272,787, dated Sept. 13, 1966. Divided and this application Apr. 13,1966, Ser. No. 543,278

7 Claims. (Cl. 23-270) This is a divisional application of patentapplication filed June 5, 1961, Ser. No. 114,727, now Patent No.3,272,787.

This invention relates to an apparatus suitable for the separation ofcatalyst or amorphous polymer from solid olefin polymers by solventextraction.

When polymers of olefin monomers are prepared over organometalliccatalyst systems, it is generally necessary to remove the catalyst fromthe polymer in the recovery process. In addition, polymers of alphaolefins frequently contain an amorphous fraction which can be removed inorder to increase the flexural modulus of the polymer. One of the mostpractical methods for removing either organometallic catalyst oramorphous fractions of polymer from solid olefin polymers is by solventextraction.

According to our invention, we have provided an improved apparatususeful in the solvent extraction of soluble matter from polyolefinsolids. The polyolefin solids containing soluble matter are contactedwith a solvent for said soluble matter under turbulent conditions in amixing vessel thereby dissolving the soluble matter in the solvent andleaving polymer solids. Separation of the resulting solution from thepolymer solids is obtained by maintaining a relatively quiescent zone ina lower extension of the mixing vessel so that the solids settletherein. The settled polymer solids are then withdrawn from thisextension and compacted While backwashing with a fresh solvent which isforced into the mixing vessel through said lower extension. The solutionof solvent and soluble matter is withdrawn from the mixing vesselthrough an upward extension thereof. The solution passes throughsaidextension in non-turbulent flow at a velocity below the transportvelocity of the polymer solids. Preferably at least a portion of thewithdrawn solution is vaporized to separate solvent from the residue ofsoluble matter. The vaporized solvent is condensed and at least a partof the resulting condensate is recirculated to the mixing vessel. Theapparatus of our invention comprises an upright elongated vessel whichhas an enlarged center section of substantially uniform cross-sectionand extended upper and lower sections having uniform cross-sectionssubstantially less than said center section, agitation means disposedwithin the center section, means for introducing feed materialcomprising the polymer solids and soluble matter to said center section,means for introducing wash liquid to the bottom of said lower section,means for withdrawing solids from the bottom of said lower section, andmeans for withdrawing liquid from the top of said upper section. In saidmixing vessel, said upper and lower sections are of suflicient length toprovide volumes substantially unaffected by the agitation means and ofsufficient diameter to permit upward liquid flow at a velocity below thetransport velocity of the polymer solids. In the preferred aspect of ourinvention, the apparatus also includes a compression auger which isconnected at its inlet end to the bottom of said lower section. Thiscompression auger contains means for removing compacted solids from itsother end and means for introducing a wash liquid to an intermediatepoint of said auger.

Therefore, an object of our invention is to provide apparatus suitablefor extracting soluble material such as catalyst or atactic polymer fromsolid polymers such as polypropylene with a minimum of contacting andseparating steps.

Another object of our invention is to provide an apparatus which enablesthe removal of catalyst and/ or atactic polymer from solid polypropylenewith a minimum of handling and pumping of slurries and solutions.

Other objects, advantages and features of our invention will be apparentto those skilled in the art from the following discussion and drawingsin which:

FIGURE 1 is a diagram of our improved contacting apparatus;

FIGURE 2 is a flow diagram of a process utilizing the apparatus of ourinvention; and

FIGURE 3 is a fiow diagram of another process utilizing the apparatus ofour invention for the removal of both catalyst and amorphous polymerfrom a normally solid polypropylene.

While our invention can be applied to advantage in its various aspectsto polymers of olefins broadly, it is particularly useful in therecovery of polymers of alpha olefins from a polymerization process overan organometallic catalyst system. Ordinarily these alpha olefins willhave from 3 to 6 carbon atoms per molecule such as propylene, l-butene,l-pentene, 4-methyl-1-pentene, 3-. methyl-l-butene,3,3-dimethyl-1-butene, and the like. In a preferred aspect of ourinvention, polypropylene is treated to remove catalyst and/or atacticfraction therefrom. In the organometallic catalyst systems which areused in the processes to which our invention is preferably directed, theorganometal employs a non-transition metal of Groups I, II, or III ofthe periodic system; for example, aluminum, beryllium, zinc, magnesium,lithium, or sodium in which the metal is attached to at least onehydrocarbon radical and the remaining valences, if any, are satisfied byhalogen or hydrogen. Complex alkyls of aluminum and alkali metals, forexample, lithium aluminum tetrapropyl, are sometimes used. Of thesecatalysts, We prefer the dialkylaluminum chlorides or bromides in whichthe alkyl radicals have from 1 to 8 carbon atoms. In the catalystsystem, the organometal is used with a transition metal compound such asthe halides of the Groups IV to VI metals, for example, titanium,vanadium, zirconium, hafnium, thorium, uranium, niobium, tantalum,chromium, molybdenum or tungsten. Of these, the chlorides of titaniumare preferred and titanium trichloride is the best in the polymerizationof propylene. The apparatus of our invention is particularly useful forthe removal of catalyst such as diethylaluminum chloride and titaniumtrichloride. Preferably, the polymerization is carried out in the liquidmonomer although an inert diluent can be employed. Temperatures in therange of about to 160 F. and residence times of about 1 to 15 hours arepreferred for the polymerization of alpha olefins such as propylene. Thecatalyst is used in a weight ratio of about 0.5:1 to 20:1, preferablyabout 1:1 to 4.5:1 TiCl to dialkylaluminum halide.

In the polymerization efiiuent the ratio of polymer to catalyst wouldordinarily range from about to 1000,

or higher, pounds of polymer per pound of catalyst. In mostapplications, it is desirable that even minute amounts of catalyst beremoved prior to fabrication of the polymer. Solvent extractiontechniques are ordinarily used for this purpose and a number of suitablesolvents are known for this operation. Solvents such as alcohols,ketones,

amines, glycols, ethers, organic acids and the like can be employed. Weprefer to use aliphatic alcohols having about 1 to 5 carbon atoms, orlow molecular weight aliphatic acids having about 2 to 8 carbon atomsper molecule, or anhydrides of these acids. Examples of the preferredsolvents for catalyst removal are methanol, ethanol, propanol,isopropanol, butanol, pentanol, acetic acid, propionic acid, aceticanhydride, propionic anhydride and the like..The polymer as it isremoved from the polymerization zone is in the form of relativelyfinely, divided solids, ordinarily of a size that will pass through 20mesh (US. Standard Sieve). The amount of solvent can vary widelydepending upon the amount of catalyst in the polymer but ordinarily atleast enough solvent is used to slurry the polymer, even though inertdiluent or liquid monomer may also be present. The optimum amount ofsolvent required in order to make the desired extraction to meet thepolymer specification can readily be determined in each case.

The alpha olefin polymers and particularly polypropylene ordinarilycontain at least some atactic polymer in addition to the isotacticfraction which predominates. The amount of atactic polymer is usually inthe range from about 15 percent of the, total polymer to a negligibleamount. Hydrocarbon solvents are ordinarily used for this extraction andthe hydrocarbon solvent chosen depends on the. amount of polymer it isdesired to extract since the solubility of the polymer fractions varysomewhat from solvent to solvent. Normally liquid hydrocarbons are mostfrequently used having from 5 to 12 carbon atoms per molecule andpreferably normal paraflins such as npentane, n-hexane, or n-heptane areemployed. Here again the amount of solvent employed depends upon theamount of amorphous polymer which is to beremoved but will ordinarily beat least enough to slurry the polymer and insure good mixing in themixing vessels.

Referring now to FIGURE 1 of the drawings, the apparatus of ourinvention will be described. The apparatus.

enables substantial savings in equipment and especially in pumps since'all of the mixing and separation are carried out in one vessel andmaximum advantage is taken of gravity flow in the contacting andseparating the poly mer and solvent. In the preferred embodiment of ourapparatus as shown in FIGURE 1, the mixing vessel has a verticallyelongated cylindricalshell 10 which together with top closure 11 andbottom closure 12 define a central mixing volume where most of thecontacting between the polymer. solids and solvent occurs. A portion ofthis shell 10 has been cut away to show a centrally disposed agitator 13within the mixing vessel. Agitator 13 is mounted on shaft 14 which isconnected to motor 16 or anequivalent prime mover mounted on top of thevessel. Shaft 14 passes through a packing gland 17 in top closure 11.Feed conduit 18 is provided centrally disposed in shell 10, preferablyadjacent the zone of mixing created by agitator 13. Polymer solids withthe associated soluble material which is to be removed by extraction isintroduced through feed conduit 18. The proportions of shell 10 can varysubstantially provided sufficient agitation means are provided to insureefficient mixing and utilization of the tank volume. Preferably thelength to diameter ratio of shell 10 is from about 1:1 to 2:1.

Depending from the lower end of the center section of the mixing vesselis a settling leg which is defined by an elongated cylindrical shell 19attached at its upper end to the bottom closure member 12 and shell 10'.Although shell 19 can be connected in other positions on closure 12,,itshould be offset from the center line of shell 10 andpreferablypositioned at the periphery of shell 10 or affixed thereto at at leastone point as shown in FIGURE 1. By offsetting the settling leg in thismanner, a minimum of the turbulence created by agitator 13 istransferred into the settling leg so that a relatively quiescent zone isdeveloped with a minimum of leg length. The diameter of shell 19 shouldbe substantially less thanthe diameter of shell 10 and preferably isabout ,4; to the diameter of shell 10. The length to diameter ratioshould be at least about 3:1 to 10:1 in order to insure a relativelyquiescent zone at its lower extremity. Preferably the length to diameterratio of shell 19 is in the range of about 3:1 to 7:1 and the length ofshell 19 is ordinarily about to 1 /2 times the length of shell 10.

While a turbulent zone is maintained within shell 10 to insure efficientcontact between the polymer and the solvent, the settling leg defined byshell 19 is proportioned to provide a settling rate of polymer solids ofabout 0.1 to 3 feet per minute. The settling polymer solids are alsocontacted with rising solvent which enters at the bottom of settlinglegso that the length of this leg should be sufiicient to insure adequatewashing of the polymer.

The bottom of shell 19 is connected by conical closure member 20 toinlet 21 of compression auger 22. Compression auger 22 can be a commoncompression cxtruder or pressurized auger conveyor with a restrictedopening at its discharge end to insure that a compacted mass of polymersolids is built up with the discharge end of the auger. The screw ofauger 22'is driven by motor 23 and the polymer solids are compacted andultimately forced out of auger 22 through discharge opening 24. It isessential that, a compacted mass of polymer solids be built up on thedischarge end of auger 22 in order that a seal be maintained and thereis no loss of pressure from the mixing vessel. Also, as the polymersolids are forced by the auger into the compacted mass, the more fluidmaterial, that is the solvent, is expressed from the polymer solids andforced backwardly into the settling leg. Ad- 1 be introduced to thebottom of the settling leg through conduit 27. Substantially all of thefresh solvent introduced to the extractionprocess enters by way of anger22 or conduit 27 and travels upwardly through the settling leg definedby shell 19. This fact must be borne in mind in the proportioning ofshell 10 so that sufficient diameter is provided that the upward flow ofsolvent therethrough does not exceed the transport velocity of thepolymer solids but instead enables the settling rate indicated above.

Extending from the upper portion of the central section of the mixingvessel is a rising leg as defined by shell 28 which is attached at itslower end to top enclosuremember 11 and shell 10. For the same reasonsas pointed out in connection with the settling leg, it is desirable thatthe rising leg be offset near or at the periphery of shell 10 so that aminimum of turbulence is transferred from the contacting zone into therising leg. The proportions of the rising leg are approximately the sameas given in connection with the settling leg and the diameter of therising leg must also be large enough that the velocity of the risingsolution does not exceed the transport velocity of the polymerparticles. The upper portion of shell 28 is connected -by conicalclosure member 29 to a solution withdrawal conduit 30. The solvent canbe recovered from this solution and is returned to the mixing vessel,entering through conduit 31 in shell 10. Additional entry ports of thisnature can be provided if desired.

Referring now to FIGURE 2, there is shown a process in which theabove-described mixing and separation apparatus is used to goodadvantage. Propylene and catalyst are introduced to a reactor 32 ofconventional design and provided with the necessary agitation andtemperapropylene feed and suflicient titanium trichloride is added at arate of about 0.0001 to 0.001 pound per pound of propylene feed andsufficient titanium trichloride is added for a productivity of about 100to 1,500 pounds of polypropylene per pound of TiCl Polymer settles fromreactor 32 in settling leg 33 and passes into compression auger 34driven by motor 36. Fresh propylene can be introduced into compressionauger 34 and/or into the lower portion of settling leg 33 to passcountercurrently to the polymer and wash catalyst back into the reactor.The reactor effluent is then passed through a pressure reducing valve 37into flash dryer 38. Unreacted propylene which has served as thereaction medium and which is carried out of the reactor with the polymersolids is vaporized in flash dryer 38 and removed overhead throughconduit 39. This unreacted propylene is recovered and after purificationcan be returned to the polymerization reaction. Polymer solids whichhave thus been separated from the unreacted monomer fall intocompression auger conveyor 35 driven by motor 40 and are passed throughvalve 41 into reslurry vessel 42. S01- vent from a source to bedescribed enters reslurry vessel 42 by way of conduit 43 and a pumpableslurry is formed therein by agitator 44. This slurry is then passed viaconduit 46 to pump 47 and pressurized via conduit 48 into extractionvessel 49.

When removing catalyst from polypropylene, it is desirable that anextraction temperature of about 2.50 to 300 F. be maintained and withthe solvents commonly used, such as isopropyl alcohol, an elevatedpressure is required to keep the solvent in the liquid phase. Since anelevated pressure is required in contacting vessel 49, it is necessarythat the polymer solids removed from flash dryer 38, be reslurried sothat they can be pumped by pump 47 to a vessel of elevated pressure.

As described in connection with the apparatus shown in FIGURE 1, thepolymer solids pass through settling leg 50 into compression auger 51while fresh alcohol introduced to auger 51 via conduit 52 flowscountercurrently to the polymer passing therethrough. Compacted polymersolids are then forced by way of conduit 53 into dryer hopper 54. Indryer hopper 54, the polymer solids are contacted with heated inert gasthereby vaporizing the residual solvent which has been retained on thesolids.

Polymer solids are again passed to auger conveyor 56 which is driven bymotor 57 and are forced through valve 58 into conveying system 59. Inertgas in introduced by way of conduit 60 and flows back through augerconveyor 56 into dryer hopper 54 vaporizes solvent from the polymersolids. Blower 61 provides a stream of air or inert gas which conveysthe polymer solids through conduit 59 into cyclone collector 62 fromwhich the polymer solids drop into storage container 63.

Clarified solution of alcohol and dissolved catalyst rises in rising leg64 connected to the top of contacting vessel 49 and passes throughconduit 66 into receiving vessel 67. From vessel 67 the solution ispassed by pump 68 through cyclone collector 69 wherein entrained polymersolids are removed and returned to contacting vessel 49 by way ofconduit 70. A solution stream passing through conduit 71 from collector69 is divided and a portion thereof is passed through conduit 72 andheated in heat exchanger 73. This heated solution is then passed throughconduit 74 and combined with the incoming polymer slurry in conduit 48.The desired temperature in mixing vessel 49 can thus be maintained. Theremainder of the solution in conduit 71 is passed through conduit 76into reboiler or fractionation column 77. Solution in reboiler 77 iscirculated by pump 78 through heater 79 and back into the reboiler sothat solvent is evaporated leaving a residue of catalyst and alcoholwhich is removed from the system through conduit 80. The vaporizedsolvent passes overhead from reboiler 77 through conduit 81 to condenser82 wherein the solvent is condensed and the condensate is passed toreceiver 83.

Uncondensed gases comprising monomer and some alcohol are vented fromreceiver 83 through conduit 84. The condensed solvent is passed fromreceiver 82 by pump 86, a portion of the condensate being returned byway of conduit 87 to reboiler 77 and the remainder being passed byconduit 43 to reslurry vessel 42 as previously described.

Inert gases carrying volatilized solvent from dryer hopper 54 passthrough condenser 88. The solvent is thus condensed and thereafterseparated from the inert gas in receiver 89. Inert gases pass overheadthrough conduit 90 while the solvent is passed by pump 91 throughconduit 92 joining the solvent in conduit 76 on its way to reboiler 77.It can be seen from this process that very eliicient use is made of thecatalyst solvent. The only fresh solvent which is added is thatnecessary to oflset the solvent removed with the residual catalyst fromreboiler 77 and as uncondensed solvent vapors which are vented with theinert gas in conduit 90 and with the unreacted monomer in conduit 84.The process also enables the recovery of dry polymer solids withrelatively little handling. since most of the liquid is removed from thesolids in the compression auger 51 which also serves as a countercurrentcontacting zone for the polymer solids and fresh solvent.

- As has been previously explained, the process of our invention canalso be used to advantage for the removal of amorphous polymer from asubstantially crystalline polymer. A process in which two contactingsteps are used in series for the removal first of catalyst and then ofatactic polymer is shown in FIGURE 3. The same numerals are used inFIGURE 3 as are used in FIG- URE 2 to indicate corresponding features.In FIGURE 3, however, the reactor efiluent which is predominantlypolymer solids with the associated catalyst and unreacted propylene ispassed from auger 34 directly into the contacting vessel 49. In place ofauger 34, it is possible to use a fluid transporting medium ofpropylene, fresh alcohol or recycle alcohol from accumulator 83 to carrythe polymer to vessel 49. The extraction with alcohol in contactingvessel 49 is the same as described in connection with FIGURE 2 exceptthat the solution in rising leg 64 is passed directly through conduit tocolumn 77 and vaporized solvent from column 77 which is condensed andaccumulated in receiver 83 is passed in part through conduit 93 toheater 94 and thence through conduit 96 returning directly to thecontacting vessel 49. In the embodiment shown in FIGURE 3, theuncondensed gases from receiver 83 and conduit 84 contain a substantialpropylene fraction since all of the unreacted propylene from theeffluent polymer solids is removed in the catalyst extraction step. Thegases in conduit 84 are, therefore, passed to propylene recovery stepsso that this propylene can be returned to the reactor. Since thepropylene is recovered from the reactor eflluent in this manner, thereis no need for an intermediate pressure reducing stage asshown in flashvessel 38 of FIGURE 2. By not reducing the pressure on thepolymerization eflluent in order to remove unreacted propylene, the useof a reslurry vessel is avoided and the polymer can be passed directlyinto pressurized contacting vessel 49. Since a reslurry vessel is notused, that condensed solvent from receiver 83 which is not returneddirectly to column 77, is passed to contacting vessel 49 and thetemperature in this contact vessel is maintained by heating this solventreturn stream in heater 94. It can be seen that there is substantialsavings in equipment in this embodiment over that shown in FIGURE 2 byremoving the unreacted propylene in the catalyst extraction step. On theother hand, substantially higher amounts of solvent are removed from theextraction system through conduit 84. In FIGURE 3, the condensed solventwhich is removed form the polymer solids by the inert gas in conveyor 56The dried polymer solids from conveyor 56 pass through valve 58 into asecond contacting vessel 98 for the removalof atactic polymer. Likevessel 49, vessel 98 is equipped with a settling leg 99 and a rising leg100. The polymer solids are contacted at about atmospheric pressure anda temperature in the range of about 150 to 200 F. with a normally liquidparafiinic hydrocarbon, preferably normal heptane. The polymer solidssettle in settling leg 99 and pass into compression auger 101 which ispowered by motor 102. Compression auger 101 acts similarly tocompression auger 51 and expresses solvent from the polymer solids whileat the same time fresh solvent is introduced to the auger throughconduit 103 passing countercurrently to the solid polymer and extractingmore of the soluble polymer therefrom. The polymer solids having had asubstantial amount of the .atactic polymer removed are then passedthrough conduit 104 to conveyor 106 which is powered by motor 107. Inconveyor 106, the solids are contacted with an inert gas to vaporize theresidualnormal heptane associated therewith. The solids are then passedthroughconduit 108 and valve 109 into pneumatic conveyor conduit 59through which the polymer solids are carried to cyclone collector 62 andstorage bin 63. Inert gas is introduced through conduit 110 and passesin countercurrent flow to the polymer solids in conveyor 106, vaporizingnormal heptane. The vaporized normal heptane and inert gas are passedfrom conveyor 106 through conduit 111 to condenser TABLE I.MATERIALBALANCE a tower reactor employing a temperature of 100 F., a pressure of250 p.s.i.a., and a residence time of 8 hours. Liquid propylene which isthe reaction diluent .is evaporated, condensed and recycled to controlthe temperature of the exothermic reaction. The solids content in thereactor isabout 25 percent. The effluent stream is reduced to a pressureof 16.7 p.s.i.a. and a temperature of 150. F. in a drying zone tovaporize most of the unreacted propylene and the material which is notvaporized is reslurried in isopropyl alcohol at atmospheric pressure.This slurry is then pumped to a contacting vessel maintained at apressure of 175' p.s.i.a. and, a temperature of 280 F. wherein theisopropyl alcohol and the solid polymer are intimately contacted by-mechanical agitation for removal of catalyst. The polymer solids settlein a settling leg of the vessel and are contacted with fresh isopropylalcohol ,in a compression auger which is 8 inches in diameter and 20feet long. The solids are then contacted with an inert gas at a pressureof about 16.7 p.s.i.a. and 200 F. to evaporate the residual associatedalcohol from the polymer. The dry solids are then passed to storage. Asolution of isopropyl alcohol and catalyst which has been removed from arising leg of the contacting vessel is boiled for evaporation of thealcohol which is condensed and recycled to the reslurry tank. Thecontacting vessel has a center shell section 6 feet in diameter and 10feet in length and each of the rising and settling legs is 20 inches indiameter and 10 feet in length. The stream flows in pounds per hour areshown in Table .I as a material balance with reference to conduit asnumbered in FIGURE 2.

FOR FIGURE 2 (POUNDS PER HOUR) Reactor Reactor Line Line Line Lino Line.Line Line Line Line Line Lino Line Line Polymer Feed Efliuent 39 43 4653 66 70 74 84 60 92 Storage Polypropylena 3, 715 3, 715 3, 715 30 30 3,715 Titanium Trichloride... 5. l6 5. 6 5. 6 0.5 15 Trace 9. 9 5.1Diethylaluminum Chloride 1.3 1.3 1.3 .1 1.3 n-Decane 2 2 2 Propylene 4,300 390 332 611 669 57 Propane 43 43 37 61 5. 9 Hydrogen 0.05 0. 05 0.05Isopropyl Alcohol 15, 640 15,640 30 300 95 12 Inert Gas w 150 SolublePolymer 195 915 195 112. The condensed solvent and inert gas 1sseparated EXAMPLE II from the condensate and vented through line 116.

A clarified; solution of solvent and atactic polymer rises fromcontacting vessel 98 in rising leg 100 and passes overhead throughconduit 117 and pump 118 to gas fired flash preheater 119. The heatedsolution is then passed through conduit 120 to flash tank 121. Thesolvent which is flashed into vapor in flash tank 121 passed overheadthrough conduit 122 to condenser 123 and then as condensate to receiver124. This condensate is returned through conduit 126 by pump 127 andconduit 128 to contacting vessel 98. The solvent which has been removedfrom the polymer solids by inert gas and collected in receiver 114 ispassed through conduit 129 by pump 130 and joins the solvent in line128' being returned to contacting vessel 98. A residue of atacticpolymer is removed from fiash vessel 121 through conduit 131 to storagedrum 132 for suitable disposal.

In order to illustrate the applicability to polymerization processes ofour improved apparatus, the following examples are given.

EXAMPLE I Propylene is polymerized continuously over a catalyst oftitanium trichloride and diethylaluminum chloride in Propylene iscontinuously polymerized over a catalyst of diethyl-aluminum chlorideand. titanium trichloride in a pipe-loop reactor at a temperature of F.,a pres? sure of 650 p.s.i.a., and a residence time of 3 hours. The

In this vessel, the polymer solids are contacted with iso-,

propyl alcohol in the same manner as described in connection withExample I. The polymer solids after drying with inert gas are passed toa second contact vessel where they are mixed with normal heptane atatmospheric pressure and at a temperature of 180 F. Atacticpolymer isdissolved by the normal heptane and the resulting solution is passedthrough a rising leg and, then to a heater where it is flashed at apressure of 90 p.s.i.a. and 350 F. Atactic polymer is removed as bottomsand the normal heptane is recirculated to the contacting vessel.Polymer. solids are dried with inert gas and the evaporated normalheptane is likewise recirculated. The material balance for this processis given in Table II with reference to the conduits as numbered inFIGURE 3.

TABLE II.MATERIAL BALANCE FOR FIGURE 8 (POUNDS PER HOUR) Reactor LineLine Line Line Line Line Line Line Line Line Line Line Line Line PolymerEffluent 52 53 60 80 84 90 96 97 103 104 110 116 117 131 StoragePropylene Propane Titanium Trichloride Diectlhylalmninum Chlorr e n-Decane Isopropyl Alcohol. n-Heptane. Inert Gas Isotactie Polyrne As willbe apparent to those skilled in the art, various modifications can bemade in our invention without departing from the spirit or scopethereof.

We claim:

1. Contacting apparatus for extraction of soluble matter fromparticulate solids comprising, in combination:

(a) an upright, elongated vessel having an enlarged center section ofsubstantially uniform cross-section and vertically extended upper andlower sections having uniform cross-sections substantially less thansaid center section, said upper and lower sections being positioned atthe periphery of said center section;

(b) agitation means disposed within said center section;

(c) means for introducing feed material comprising solids and solublematter to the intermediate portion of said center section;

(d) means for introducing wash liquid to the bottom of said lowersection;

(e) means for withdrawing liquid from the top of said upper section;

(f) means for withdrawing solids from the bottom of said lower sectionsaid withdrawing means being adapted to maintain a pressure seal withinsaid vessel; and

g) said upper and lower sections being of sufficient length and diameterto provide volumes so that materials contained therein are substantiallyunefifected by turbulence created by said agitation means, the minimumdiameter of said upper and lower sections being further characterized asbeing sufiicient to permit upward liquid flow at a velocity below thetransport velocity of said solids.

2. Contacting apparatus according to claim 1 wherein said means forwithdrawing solids from the bottom of said lower section is acompression auger connected at its inlet end to the bottom of said lowersection, further including means for introducing wash liquid to anintermediate point of said auger.

3. The apparatus according to claim 2 further comprising, incombination, a vaporizing means connected to said liquid withdrawalmeans to receive liquid from the top of said upper section, meansconnected to the top of said vaporizing means for condensing vaporsformed therein, means for returning condensate so formed to the centersection of said elongated vessel, and means connected to the bottom ofsaid vaporizer to receive concentrated liquid therefrom.

4. The apparatus according to claim 3 further comprising, incombination, a receiving vessel connected to the top of said uppersection, conduit means with a pump disposed therein connecting saidreceiving vessel to a cyclone separator which has a solids outlet and asolution outlet, conduit means connecting the solids outlet of saidseparator with the center section of said elongated vessel, and aconduit means connecting the solution outlet of said separator with saidvaporizing means.

5. An apparatus according to claim 1 further characterized in that saidcontacting vessel has a height to diameter ratio in the range of from1:1 to 2:1, said extended the height of said vessel and about 3 to 10times said upper section, said extended lower section havingapproximately the same proportions as said upper section.

6. The apparatus according to claim 1 wherein:

(a) said center section comprises a vertical elongated cylindrical shellhaving a length to diameter ratio in the range of from 1:1 to 2:1 andhaving top and bottom closure means defining a volume therein;

(b') said extended upper section comprises a vertically elongatedcylindrical shell, connected at its lower end to said top closure meansso that the volume defined thereby communicates with said volume withinsaid center section, having a length to diameter ratio in the range offrom 3:1 to 10: 1, a diameter about /5 to A the diameter of said centersection and a length about to 1 /2 the length of said center section;

(c) said liquid withdrawing means comprises a conical closure connectingthe upper end of said extended upper section to a conduit;

(d) said extended lower section comprises a vertically elongatedcylindrical shell, connected at the upper end to said bottom closuremeans so that the volume defined thereby is communicating with saidvolume within said center section, having approximately the samedimensional proportions as said extended upper section;

(c) said means for withdrawing solids comprises a substantiallyhorizontal compression anger with a conical closure connecting the lowerend of said extended lower section with the inlet end of said auger anda means for removing compacted solid from the dis charge end of saidauger;

(f) said means for introducing feed material into said center sectioncomprises a conduit connected to about the midpoint of said centersection;

(g) said agitation means is disposed centrally within said centersection; and

(h) said means for introducing wash liquid comprises conduit meansconnected to the lower end of said lower section and conduit meansconnected to an intermediate portion of said auger.

7. Contacting apparatus for the extraction of catalyst from particulatepolymer solids comprising, in combination:

(a) an elongated vessel having .a first vertically elongated cylindricalshell with a length to diameter ratio in the range of from 1:1 to 2: 1;

(b) top and bottom closure means confining the volume within said firstshell;

(0) a second vertically elongated cylindrical shell connected at itslower end to said top closure means with said first shell defining avolume communicating with said volume within said first shell, saidsecond shell I (e) a third vertically elongated cylindrical shellconnected at its upper end to said bottom closure means with said firstshell defining a volume communicating with said volume within said firstshell, said third shell being dimensionally proportioned like saidsecond shell;

(f) a substantially horizontal compression auger;

(g) a conical closure connecting the lower end of said third shell withthe inlet end of said auger;

(h) feed conduit means connected to about the midpoint of said firstshell;

(i) agitation means disposed centrally within said first shell;

(j) means for removing compacted solids from the discharge end of saidauger;

(k) conduit means for introducing wash liquid into the lower end of saidthird shell and into an intermediate portion of said auger;

(1) a separator assembly connected to the upper portion of said secondshell and adapted to receive liquid therefrom, said separatorassemblyincluding a receiving vessel, a pump, and a cyclone separatorhaving a solids outlet and a liquid outlet in that order;-

(m) conduit means connecting the solids outlet of said cyclone separatorwith about the midpoint of said first shell;

(n) conduit means connecting the liquid outlet of said separator to avaporizing means;

(0) conduit means connecting the vapor outlet of said vaporizing meansto a condenser;

(p) conduit means connected to said condenser for introducing condensedsolvent vapors into about the midpoint of said first shell; and

(q) means connected to the bottom of said vaporizing means for removingrecovered catalyst.

References Cited WILBUR L. BASCOMB, JR., Primary Examiner.

NORMAN YUDKOFF, Examiner.

S. J. EMERY, Assistant Examiner,

1. CONTACTING APPARATUS FOR EXTRACTION OF SOLUBLE MATTER FROMPARTICULATE SOLIDS COMPRISING, IN COMBINATION: (A) AN UPRIGHT, ELONGATEDVESSEL HAVING AN ENLARGED CENTER SECTION OF SUBSTANTIALLY UNIFORMCROSS-SECTION AND VERTICALLY EXTENDED UPPER AND LOWER SECTIONS HAVINGUNIFORM CROSS-SECTIONS SUBSTANTIALLY LESS THAN SAID CENTER SECTION, SAIDUPPER AND LOWER SECTIONS BEING POSITIONED AT THE PERIPHERY OF SAIDCENTER SECTION; (B) AGITATION MEANS DISPOSED WITHIN SAID CENTER SECTION;(C) MEANS FOR INTRODUCING FEED MATERIAL COMPRISING SOLIDS AND SOLUBLEMATTER TO THE INTERMEDIATE PORTION OF SAID CENTER SECTION; (D) MEANS FORINTRODUCING WASH LIQUID TO THE BOTTOM OF SAID LOWER SECTION; (E) MEANSFOR WITHDRAWING LIWUID FROM THE TOP OF SAID UPPER SECTION; (F) MEANS FORWITHDRAWING SOLIDS FROM THE BOTTOM OF SAID LOWER SECTION SAIDWITHDRAWING MEANS BEING ADAPTED TO MAINTAIN A PRESSURE SEAL WITHIN SAIDVESSEL; AND (G) SAID UPPER AND LOWER SECTIONS BEING OF SUFFICIENT LENGTHAND DIAMETER TO PROVIDE VOLUMES SO THAT MATERIALS CONTAINED THEREIN ARESUBSTANTIALLY UNEFFECTED BY TURBULENCE CREATED BY SAID AGITATION MEANS,THE MINIMUM DIAMETER OF SAID UPPER AND LOWER SECTIONS BEING FURTHERCHARACTERIZED AS BEING SUFFICIENT TO PERMIT UPWARD LIQUID FLOW AT AVELOCITY BELOW THE TRANSPORT VELOCITY OF SAID SOLIDS.